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<head><meta charset="utf-8"><title>Add a `NOOP_METHOD_CALL` lint for methods whic… lang-team#67 · t-lang/major changes · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/index.html">t-lang/major changes</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html">Add a `NOOP_METHOD_CALL` lint for methods whic… lang-team#67</a></h3>

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<a name="215385883"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215385883" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> triagebot <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215385883">(Nov 02 2020 at 22:06)</a>:</h4>
<p>A new proposal has been announced: <a href="https://github.com/rust-lang/lang-team/issues/67">Add a <code>NOOP_METHOD_CALL</code> lint for methods which should never be directly called #67</a>. It will be announced at the next meeting to try and draw attention to it, but usually MCPs are not discussed during triage meetings. If you think this would benefit from discussion amongst the team, consider proposing a design meeting.</p>



<a name="215410562"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215410562" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Alexander Ronald Altman <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215410562">(Nov 03 2020 at 04:03)</a>:</h4>
<p>For <code>clone</code> and <code>to_owned</code>, would it not make sense to have it fire on anything <code>Copy</code>?</p>



<a name="215662579"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215662579" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> tmandry <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215662579">(Nov 05 2020 at 01:35)</a>:</h4>
<p>I definitely support this, it's another "guide rail" for people who are learning.</p>



<a name="215809650"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215809650" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> scottmcm <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215809650">(Nov 06 2020 at 06:16)</a>:</h4>
<p>As I said on the compiler MCP conversation, <span aria-label="+1" class="emoji emoji-1f44d" role="img" title="+1">:+1:</span> on the general idea.  I see that this one avoided the implementation discussion that I had concerns with in the other one.</p>



<a name="215933003"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215933003" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Aaron Hill <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215933003">(Nov 07 2020 at 05:12)</a>:</h4>
<p><span class="user-mention silent" data-user-id="262628">Alexander Ronald Altman</span> <a href="#narrow/stream/243200-t-lang.2Fmajor-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367/near/215410562">said</a>:</p>
<blockquote>
<p>For <code>clone</code> and <code>to_owned</code>, would it not make sense to have it fire on anything <code>Copy</code>?</p>
</blockquote>
<p>Yeah, that sounds good</p>



<a name="215933062"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215933062" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Aaron Hill <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215933062">(Nov 07 2020 at 05:14)</a>:</h4>
<p>stabilizing that kind of functionality for users would require a fair amount of design work - making <code>to_owned</code> fire on <code>Copy</code> types would require marking the blanket <code>impl&lt;T: Clone&gt; ToOwned for T</code> for receiver types that satisfy an additional bound (<code>Copy</code>)</p>



<a name="215933069"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215933069" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Aaron Hill <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215933069">(Nov 07 2020 at 05:14)</a>:</h4>
<p>but it shouldn't pose any problems for the internal implementation for libstd types/traits</p>



<a name="215942837"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215942837" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> scottmcm <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215942837">(Nov 07 2020 at 07:27)</a>:</h4>
<p><span class="user-mention silent" data-user-id="125294">Aaron Hill</span> <a href="#narrow/stream/243200-t-lang.2Fmajor-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367/near/215933003">said</a>:</p>
<blockquote>
<p><span class="user-mention silent" data-user-id="262628">Alexander Ronald Altman</span> <a href="#narrow/stream/243200-t-lang.2Fmajor-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367/near/215410562">said</a>:</p>
<blockquote>
<p>For <code>clone</code> and <code>to_owned</code>, would it not make sense to have it fire on anything <code>Copy</code>?</p>
</blockquote>
<p>Yeah, that sounds good</p>
</blockquote>
<p>I think that makes it <a href="https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy">https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy</a> -- not that that's a bad thing.</p>



<a name="215965969"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215965969" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Aaron Hill <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215965969">(Nov 07 2020 at 17:54)</a>:</h4>
<p>this lint is more general, since it will fire on a bunch of other methods as well</p>



<a name="215966004"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/215966004" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Aaron Hill <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#215966004">(Nov 07 2020 at 17:55)</a>:</h4>
<p>some of which are only implemented for <code>&amp;T</code>, not <code>T: Copy</code> (e.g. <a href="https://doc.rust-lang.org/std/ops/trait.Deref.html#impl-Deref-5">Deref</a>)</p>



<a name="216094032"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216094032" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> triagebot <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216094032">(Nov 09 2020 at 14:51)</a>:</h4>
<p><span class="user-group-mention" data-user-group-id="1977">@T-lang</span>: Proposal <a href="https://github.com/rust-lang/lang-team/issues/67#issuecomment-724061616">#67</a> has been seconded, and will be approved in 10 days if no objections are raised.</p>



<a name="216094147"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216094147" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216094147">(Nov 09 2020 at 14:52)</a>:</h4>
<p>Copying my comment from the issue </p>
<blockquote>
<p>I'm a bit torn on this one. I'd like it if we developed and published clearer criteria for what sort of lints belong in rustc -- I remember that @oli-obk actually took a stab at that. I don't know that this could be a common source of bugs but certainly confusing compilation errors (I've experienced that myself on occasion...). In any case, I'd be ok seeing a PR go up, and I'd expect an FCP on that PR.</p>
</blockquote>



<a name="216102666"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216102666" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216102666">(Nov 09 2020 at 15:51)</a>:</h4>
<p>Note that clippy already lints this as <code>clone_double_ref</code>:</p>
<div class="codehilite"><pre><span></span><code>error: using `clone` on a double-reference; this will copy the reference instead of cloning the inner type
 --&gt; src/main.rs:9:2
  |
9 |     val.clone(); // WARNING: noop method call
  |     ^^^^^^^^^^^
  |
  = note: `#[deny(clippy::clone_double_ref)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_double_ref
help: try dereferencing it
  |
9 |     &amp;(*val).clone(); // WARNING: noop method call
  |     ^^^^^^^^^^^^^^^
help: or try being explicit if you are sure, that you want to clone a reference
  |
9 |     &lt;&amp;Foo&gt;::clone(val); // WARNING: noop method call
  |     ^^^^^^^^^^^^^^^^^^
</code></pre></div>



<a name="216102960"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216102960" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216102960">(Nov 09 2020 at 15:52)</a>:</h4>
<p>As per <a href="https://github.com/rust-lang/rfcs/blob/master/text/2476-clippy-uno.md#lint-audit-and-categories">https://github.com/rust-lang/rfcs/blob/master/text/2476-clippy-uno.md#lint-audit-and-categories</a> this lint belongs to the <code>Correctness</code> class</p>



<a name="216103068"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216103068" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216103068">(Nov 09 2020 at 15:53)</a>:</h4>
<p>correctness lints are those we consider as candidates for moving to rustc</p>



<a name="216103084"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216103084" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216103084">(Nov 09 2020 at 15:53)</a>:</h4>
<p>cc <span class="user-group-mention" data-user-group-id="3456">@T-clippy</span></p>



<a name="216123017"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216123017" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> flip1995 <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216123017">(Nov 09 2020 at 18:13)</a>:</h4>
<p>Thanks for the ping! If a PR should go up, please ping the Clippy team for proper deprecation of the Clippy lint.</p>



<a name="216123436"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216123436" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216123436">(Nov 09 2020 at 18:16)</a>:</h4>
<p>Yeah I remembered us talking about this specific lint at some point</p>



<a name="216123447"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216123447" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216123447">(Nov 09 2020 at 18:16)</a>:</h4>
<p>(and whether it was correctness...)</p>



<a name="216126563"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216126563" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Aaron Hill <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216126563">(Nov 09 2020 at 18:41)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span> I came up with the idea for this lint after seeing two people on the Rust discord get tripped up by calling <code>to_owned</code> on a reference to a non-<code>Clone</code> type. I agree that it's unlikely for this to result in a bug (i.e. code that compiles), but I think it helps clarify an otherwise confusing situation</p>



<a name="216132398"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216132398" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216132398">(Nov 09 2020 at 19:28)</a>:</h4>
<p>If I recall there were some examples where it actually did lead to a bug</p>



<a name="216132412"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216132412" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216132412">(Nov 09 2020 at 19:28)</a>:</h4>
<p>but I don't remember what they were</p>



<a name="216140878"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216140878" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> cuviper <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216140878">(Nov 09 2020 at 20:47)</a>:</h4>
<p>Just now on the users forum: <a href="https://users.rust-lang.org/t/error-message-suggestion-for-cloning-hashmap-a-when-k-or-v-dont-clone/51262">https://users.rust-lang.org/t/error-message-suggestion-for-cloning-hashmap-a-when-k-or-v-dont-clone/51262</a></p>



<a name="216173709"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/216173709" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Aaron Hill <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#216173709">(Nov 10 2020 at 05:26)</a>:</h4>
<p>That's really subtle. The generic parameters of <code>HashMap</code> didn't satisfy the required bounds, so a different impl got chosen by method resolution.</p>



<a name="217653202"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/217653202" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Aaron Hill <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#217653202">(Nov 23 2020 at 16:52)</a>:</h4>
<p>Is rustbot supposed to automatically end the final comment period?</p>



<a name="218359159"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/243200-t-lang/major%20changes/topic/Add%20a%20%60NOOP_METHOD_CALL%60%20lint%20for%20methods%20whic%E2%80%A6%20lang-team%2367/near/218359159" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/243200-t-lang/major-changes/topic/Add.20a.20.60NOOP_METHOD_CALL.60.20lint.20for.20methods.20whic.E2.80.A6.20lang-team.2367.html#218359159">(Nov 30 2020 at 23:05)</a>:</h4>
<p>no, I do that manually ..</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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